Small cartridges that hold a large quantity of carbon dioxide or other gaseous fluid therein are well known. The cartridges are commonly used to rapidly inflate items that require rapid inflation, such as life vests and life rafts.
Numerous devices have been invented that have utility in rupturing or piercing the gas cartridge and directing the gas into the item to be inflated. For example, U.S. Pat. No. 3,911,762 to Mackal et. al. shows an apparatus where the cartridge is pierced by rotating a bell crank about a pivot shaft. The rotation of the lever causes a solid piercing pin to rupture the gas cartridge.
Another inflator that includes a cartridge piercing solid pin is shown in U.S. Pat. No. 3,809,288, also to Mackal et. al.
The pressure within a typical gas cartridge is above eight hundred pounds per square inch. Accordingly, even the end wall thereof that is pierceable is strongly reinforced about its periphery so that the only pierceable part thereof is a small, central target area which has a relatively thin construction. If a pin is slightly misaligned, it will miss the thin center and the cartridge will remain unpunctured. Prior art pins, in general, have been plagued by alignment problems.
Moreover, maximum flow of gas from the cartridges is obtained when the hole created by the piercing pin is round. Prior art pins are mostly of solid construction and typically produce crescent shaped or other non-round holes. Thus, the escaping gas flows, at an inhibited rate, past the solid pin in route to the interior cavity of the inflatable article.
One prior art pin is formed by bending a flat plate into a tubular configuration, thereby producing a longitudinally extending slot therein. However, that pin has a relatively weak, elongate construction and thus it is relatively unsupported at the base into which it is driven. Another drawback of that pin is its two piece construction.
There is a need, then, for a one piece, structurally sound cartridge piercing pin that is free from misalignment problems so that it consistently pierces the thin center of the cartridge. There is a need as well for a pin that produces round punctures to maximize gas flow from the pierced cartridge. There is also a need for a truncate pin having increased structural integrity. However, the prior art, taken as a whole, neither teaches nor suggests how an improved pin could be built.